Cardiovascular disease (CVD), type 2 diabetes (T2D) and their comorbidity pose important health challenges for the United States in the coming decades. African Americans (AAs) have a greater prevalence of T2D and have higher CVD and T2D related mortality rates compared with European Americans (EAs). Environmental stress has been postulated as playing an important role in the development of CVD and T2D, particularly among AAs, but little is known about underlying physiological mechanisms linking stress to early etiology of CVD and T2D. Assessment of possible differential impact of chronic environmental stress upon longitudinal development and manifestation of preclinical markers of CVD and T2D in AAs and EAs can be accomplished only with proper control for genetic influences. Employment of a genetically and environmentally informative twin study design enables genetic variation contributing to individual variation [heritability (h2)] to be controlled for and environmental influences [environmentality = 1-h2] to be quantified. The fundamental objective of this proposal is to identify whether exposure to chronic stress is associated with development of early risk markers of CVD and T2D and whether this differs between AAs and EAs. Collecting data on 2 additional occasions in the Georgia CV Twin study (523 pairs, 302 EA and 221 AA) who will be T9.5[unreadable]3.5 yrs old will yield 5 evaluations over a crucial time span capturing the transition from childhood into adulthood. Particularly informative will be addition of new indices of sympathetic nervous system and hypothalamic-pituitary-adrenal axis activation (i.e., urinary excretion rate of norepinephrine and salivary cortisol), the metabolic syndrome (i.e., blood pressure, high density lipoprotein, triglycerides, waist circumference, fasting glucose and insulin), environmental stress (e.g., childhood trauma, job strain, perceived discrimination and unfairness, community social status) and a measure of vascular function (i.e., arterial stiffness). Relevance to public health: lncreased understanding of the role of environmental stress related factors and their underlying physiological mechanisms as contributors to health disparities between AAs and EAs will assist in earlier and better identification of youth and young adults at increased risk for CVD and T2D. It will also aid the development of more personalized primary prevention programs involving lifestyle interventions in which the role of chronic stress will be taken into account to prevent early onset of these diseases.